[talk] kill -0

[Raul Cuza]

On Fri, May 10, 2019 at 3:37 PM fire crow <fire at firecrow.com> wrote:
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>
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> On Fri, May 10, 2019, 15:32 Edward Capriolo <edlinuxguru at gmail.com> wrote:
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>> On Fri, May 10, 2019 at 3:06 PM Pete Wright <pete at nomadlogic.org> wrote:
>>>
>>>
>>>
>>> On 2019-05-10 11:59, Pete Wright wrote:
>>> >
>>> >
>>> > On 2019-05-10 11:00, Raul Cuza wrote:
>>> >> Hola People Who Use Shells,
>>> >>
>>> >> I just had someone submit a shell script using `kill -0 ${PID}` to
>>> >> test if a process is running. It exits non-zero if ${PID} isn't a
>>> >> running process and zero otherwise. But...
>>> >>
>>> >> http://nixdoc.net/man-pages/FreeBSD/kill.1.html says nothing about it.
>>> >>
>>> >> The ubuntu man page mentions it poorly with "Particularly useful
>>> >> signals include HUP, INT, KILL, STOP, CONT, and 0." Looking at `kill
>>> >> --list` there is no signal 0.
>>> >>
>>> >> And stackoverflow says
>>> >> https://stackoverflow.com/questions/11012527/what-does-kill-0-pid-in-a-shell-script-do
>>> >>
>>> >> matching what the person who submitted the PR says.
>>> >>
>>> >> Am I wrong to think this should be accomplished in a way with better
>>> >> documentation? I feel like I am nit picking.
>>> >
>>> > this seems like a bash'ism - from the bash manpage:
>>> >
>>> > SIGNALS
>>> >        When bash is interactive, in the absence of any traps, it ignores
>>> >        SIGTERM (so that kill 0 does not kill an interactive shell),
>>> > and SIGINT
>>> >        is caught and handled (so that the wait builtin is
>>> > interruptible).  In
>>> >        all cases, bash ignores SIGQUIT.  If job control is in effect,
>>> > bash
>>> >        ignores SIGTTIN, SIGTTOU, and SIGTSTP.
>>> >
>>> >
>>>
>>> heh wish i saw Jan's post before i wrote this as his reply seems to
>>> answer the real question...
>>>
>>> -p
>>>
>>> --
>>> Pete Wright
>>> pete at nomadlogic.org
>>> @nomadlogicLA
>>>
>>> _______________________________________________
>>> talk mailing list
>>> talk at lists.nycbug.org
>>> http://lists.nycbug.org:8080/mailman/listinfo/talk
>>
>>
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>> It feels safer to me to use ps route.  Even if you are counting the os to preserve the 0 behaviour I feel I would fat finger it and send a kill -1 or 2
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> or more likely fat finger to 9 which is next to 0 on a keyboard
> ~fire
>>

That's why I only run `sudo` with the partial differential equation
solver challenge plugin. If I can't solve the problem, I gotta go
home.